The invention relates to rapping shaft drive means for electrostatic precipitators and more particularly relates to the bearings for a rapping shaft for electrostatic precipitators which are supported by two elongated rod members and a bearing block for receiving the rod members in nesting relationship thereon.
Electrostatic precipitators are provided with discharge and collecting electrodes which attract particulate matter from contaminated air streams passing through the precipitators. Particulate matter or dust which piles up on these electrodes must be removed by shaking or washing of these electrodes. Normally, the shaking is accomplished by vibrators or rapping devices. Generally, such devices have a rotating shaft with tumbling hammers fixed thereto and each of the hammers strikes a rapping rod linked to one or more discharge or collecting electrodes so as to shake or vibrate them. These rotating shafts are supported by bearings which are subjected to wear and tear during the rotation of the rotating shaft with the tumbling hammers affixed thereto.
Wear and tear of the bearings is generally due to the dust content in the gases to be cleaned wherein the dust or particulate matter in the gas streams penetrate into the bearings thereby producing wear and tear of the bearings as well as the shaft. In some operations chemical components in the gas stream attribute to corrosion of the bearings and shafts. And, even further, in other operating environments, the temperature of the gases which are passing through the precipitator, which in some cases are in the neighborhood of 400.degree.C, and higher, adds to the wear and tear of these bearings and shafts. Thus, the atmosphere inside a precipitator together with the wear and tear from dust, as mentioned previously, do not allow for proper lubrication of the bearings.
In present day operations, it is common to use dry slide bearings without lubrication whereby the bearing sleeves and the shaft have to be replaced after the wear and tear has reached a certain level. For example, French Pat. No. 1,361,746 teaches dry bearings with a back rest whereby the supporting parts can be readjusted from time to time. However, wear and tear of the shaft cannot be prevented by this type of bearing. Another French patent, French Pat. No. 1,449,521, teaches a shaft resting on roller or ball bearings on which the inner rings of the bearings are sliding upon two supporting bolts so that when the roller bearing and their supporting bolts are worn they can be replaced. However, this has not completely alleviated the problem. Firstly, dust continues to penetrate into the ball bearings until the ball cage is pushed to one side and finally jammed at the supporting frame of the bearing. Secondly, in conjunction with the penetration of the dust, the outer ring of the ball bearing starts to dig a groove into the rapping shaft which after a while will have to be replaced.